I love my Hydro Flask water bottles and I take them everywhere. To work, to the gym, rock climbing and even bushwalking.
While Hydro Flask's do a great job at keeping your water cold all day long they do nothing to filter your water.
If you're drinking from potentially questionable water sources then you may want to invest in a Hydro Flask filter, which can sterilize or improve the quality of the water.
As someone who goes bush walking a lot and likes to be able to drink from the local river my Hydro Flask filter lid was one of the best additions to my bottle that I didn't even know I needed.
There aren't many options out there for Hydro Flask filters, but the options that do exist are pretty good. So here is my list of the best Hydro Flask filters.
However, before we get into exactly what the best filters are it's a good idea to quickly cover the different types of filtration so you can understand the pros and cons of each and choose the best filter for your circumstances.
Different Ways To Filter Water In Your Hydro Flask
There are just a few main ways to filter your water and each have their pros and cons. By understanding these you can make a more informed decision about what Hydro Flask filter you want to buy.
One of the easiest and most effective ways to treat water is to boil it.
The high temperatures of boiling water kills or inactivates almost all bacteria, protozoa, viruses and parasites. It is usually recommended that you boil water for 1 minute or more to get the full effect.
Boiling water is simple if you have a heat source, but can be difficult and time consuming when traveling. You also need to wait for the water to cool before consuming it.
UV light (more specifically UVC light) has been shown to be extremely effective at killing bacteria, protozoa, viruses and parasites in the water.
The Ultra Violet light disrupts the micro organisms to such a degree that it causes them to die and renders them unable to replicate and divide. This makes them inert and safe to drink.
UV light is similar in effectiveness to boiling the water, but it can be more convenient as a heat source isn't required and the water can stay cold and be drunk immediately after treatment.
The biggest considerations for UV treatment is that the water needs to be clear for this to work, as UV light cannot travel through murky water to kill the micro organisms. Also UV treatment doesn't filter any salts, minerals, chemicals or micro-plastics out of the water.
Another downside of UV lights is they require power to work. While they don't require a lot of power if your batteries go flat while you're traveling the filter won't work at all until recharged or the batteries are replaced.
Membrane/micron-filters have extremely small membranes (usually around 2 nano meters in size) that allow water to pass through but not bacteria or micro plastics.
So as water passes through the filter the bacteria and parasites are caught in the filters while water is able to pass through.
The downside of these filters is that most of them do NOT filter out viruses. They also don't remove dissolved salts, minerals, heavy metals or chemicals (except chlorine). To be fair boiling water and UV treatment don't filter these out either but they do filter out viruses.
Carbon or Activated Charcoal Filters
These filters are designed to remove things such as chemicals and heavy metals from your water.
It does this by having a carbon source which has a lot of tiny pores. Through the process of adsorption – where molecules bind to the surface of the carbon lined pores – the toxins such as lead, chlorine, fluoride, pesticides, VOCs etc are filtered out of the water or drastically reduced in quantity.
These filters aren't designed remove bacteria, protozoa, viruses or parasites – so these will need to be treated in a different way.
Ion Exchange Filters (Water Softeners)
Ion exchange filters or water softeners are designed to remove dissolved salts from water. Water with a lot of dissolved salts is called “hard water”.
This isn't dangerous to drink like bacteria latent water or water with heavy metals but it can cause calcification. Generally speaking ion exchange filters are quite large, designed for home or commercial use and it's not something you can get for a small water bottle like the Hydro Flask.
However, some filters do contain some ion exchange resins to remove some of the salts in the water making it softer.
Water purification tablets are little tablets that you put inside your water bottle that are made of chlorine, iodine and chlorine dioxide.
When these chemicals dissolve in your water they kill bacteria, parasites, protozoa and viruses or render them inert.
These tablets are effective but you MUST follow the instructions carefully and wait enough time for all the micro organisms to die.
The downsides of these tablets is they can often leave a bad taste in your water and also many people want to avoid adding chemicals to their water whenever possible.
1. BEST HYDRO FLASK FILTER – HydroCap UV Filter by Waatr
I have to rank the HydroCap as the #1 best filter for Hydro Flask bottles due to the fact that it's specifically designed for Hydro Flask bottles and has all the best features you want in a UV filter.
It fits perfectly on any wide mouth Hydro Flask bottle, is completely waterproof, has a long life lithium ion battery that is easy to recharge, a handle for easy carrying and it's backed by a 10 year warranty.
You can read my full HydroCap review where I go into detail as to how this product works and why it's such a good filter for the Hydro Flask. I now take it with me everywhere I go and have successfully used it to drink water from the local river while I've been out bushwalking.
You can also check out my video review below:
The HydroCap uses 2 x UVC lights to shine down into your Hydro Flask water bottle and effectively kill 99.99%+ of bacteria, parasites, protozoa and viruses.
There is a 1 minute cycle for water you are fairly confident in (such as tap water) and a 3 minute cycle for more questionable water sources like rivers, streams and lakes.
One of the major benefits of the HydroCap over other Hydro Flask filters below is that many membrane filters don't filter out viruses, whereas the HydroCap does effectively render viruses inert.
They do advise that you shake or swirl your water bottle while the UV treatment is active to ensure the water is fully treated.
The HydroCap is backed by third party laboratory studies (see full details) to show that it effectively kills bacteria, and UVC light in general is used in many municipal water supplies to effectively treat water.
It's important to note that as a UV treatment filter it won't actually filter out any sediments, minerals or chemicals. It also only works in clear water so that is a consideration.
I really like this product and it's become my go-to lid for my Hydro Flask and I use it to filter water wherever I go.
Unlike other filters that need to be replaced regularly the HydroCap has a 10 year warranty and is able to filter up to 16,000 gallons (60,500 L) in its lifetime. This makes it excellent value for money and one of the best and most convenient Hydro Flask filters on the market today.
This is a product I use myself regularly and can recommend with confidence, especially for people drinking from questionable water sources who want to make sure it's safe to drink.
See the latest price of the HydroCap at Amazon
(or compare to the latest price of the HydroCap at Waatr.com)
2. The Answer – Epic Water Filter For Hydro Flask
The Answer by Epic Water Filters are a lid/straw/filter combo specifically designed to fit on the wide mouth Hydro Flask bottles so you can filter water on the go.
They have an Urban Filter, which is designed for tap water and the 5-stage triple capacity filters remove lead, copper and many other metals and toxins from the water.
What I absolutely love about this product is that it's made locally in the USA and it has gone through rigorous testing with their filters being tested extensively in the USA as well as many other developed countries like the UK, Japan, Australia, New Zealand.
This filter can process 75 gallons (380 L) before needing to be replaced or are 3-4 months of regular usage.
See the latest price of The Urban Epic Water Filter at Amazon
If you're someone like me and you're going outdoor and wanting to drink from rivers, streams and lakes then the Urban filter isn't going to cut it as it doesn't filter out bacteria.
Instead you'll want the Outdoor Adventure Filter which removes 99.9999% of tap water contaminants including pathogens, bacteria, viruses, giardia, cryptosporidium and more.
It also uses a propriety American made filter that uses advanced ion exchange (water softening) and activated carbon to remove lead, chromium 6, PFOA, PFOS, chlorine, flouride, chloramine, mercury, VOCs, microplastics and metals – making it one of the most comprehensive Hydro Flask filters on the market.
You can use this to drink from almost any fresh water source (much like the HydroCap) and can process up to 100 gallons (378 L).
The downside of this product is that it does take more effort to suck your water through the filter making it more difficult to drink large quantities. Plus it'll need to be replaced more regularly than a UV filter, which makes it more expensive over the long run.
Still it's not too expensive for the advanced filtration you get and means you can confidently drink from almost any water source out there. Even water than isn't completely clear (which is something UV filters can't do).
See the latest price of the Outdoor Adventure Epic Water Filter at Amazon
3. AquaMira Water Filter Lid
AquaMira sells a range of filters for different situations and they also sell a lid that fits on any wide mouth Hydro Flask that you can attach the filter to.
The lid is a flip cap style so you tip your bottle up and suck to drink it. Doesn't need to be exactly the right straw length like the Epic Water Filters and it'll work on any wide mouth Hydro Flask, even the small ones.
It has a rubber seal so it won't leak when closed and there is a variety of different filters you can choose from according to your needs.
They have 4 mains filters:
- Everyday – A carbon filter that removes chemicals like chlorine as well as other contaminants like PFOA, PFOS, Lead, VOCs, Heavy Metals. Lasts 3 months of everyday use.
- Backcountry – Removes bacteria, protozoa and parasites so you can drink water from local rivers and streams in the outback. Filters up to 100 gallons (378 L) of water before needing to be replaced.
- Backcountry Plus – Same as the backcountry with bacteria, protozoa and parasite filtration only this can filter up to 1,000 gallons (3,780 L) meaning it'll last a lot longer.
- Worldwide – Their most advanced filter that tackles bacteria, protozoa, parasites and viruses. Filters up to 120 gallons (454 L)
The great thing about these filters is you don't need completely clear water like with the HydroCap UV filter and their full range of filters has activated carbon to help remove chemicals and heavy metals from the water.
These filters aren't too expensive, especially the Backcountry Plus which does up to 1,000 gallons before needing to be replaced. Just make sure you get the correct filter for you needs. You don't want to use the everyday filter in the rivers, for that you'll want to get the back country or worldwide filters.
See latest price of Aquamira Filter Lid at Amazon
4. SteriPen Ultra
The SteriPen is a UV light filter that kills bacteria, protozoa and viruses in your water by shooting them with UVC rays that cause them to die or be rendered inert and unable to multiply.
This works the same way as the HydroCap mentioned above however instead of being a lid that fits directly onto your Hydro Flask bottle it is a pen that you manually insert into your bottle and activate.
There are a variety of SteriPen versions but some of them use obscure, hard to find and replace battery sizes and the one that uses AA batteries is the most bulky. The SteriPen Ultra on the other hand uses a lithium ion battery that is completely rechargeable allowing you to recharge from your wall socket, car or solar power.
The SteriPen is very effective at killing bacteria, protozoa and viruses as you can see in the video down below.
To use the SteriPen you press it once for 1 L (32 oz) or water or twice for 0.5 L (16 oz) of water and then place the pen in the water and stir.
The shorter cycle will run for approximately 45 seconds with the longer cycle taking 90 seconds. You can also repeat the cycle for even more effective results.
Like with all other UV water filters this will only work in clear water and stirring is advised here because the close the UV light is to the micro-organisms the more likely they are to die. So stirring it ensures all the water comes in close contact with the UV light.
The benefits of this over the HydroCap lid is that it's more versatile and can be used in other water bottles and cups that aren't Hydro Flasks.
The downside of this product is that you need to manually stir the pen in the water making it less convenient to use. Also I personally don't love the idea of having my hands so close to UV radiation while using the device.
It's a similar price to the HydroCap UV filter, only being a little more expensive. So it's up to you if you choose the versatility of the SteriPen or the convenience and cheaper cost of the HydroCap.
See the latest price of the SteriPen Ultra at Amazon
5. Portable UV Water Filter
Just like the SteriPen this portable water filter uses UV-C light to kill bacteria, protozoa and viruses in your water.
It purifies 16 oz (0.5 L) in 48 seconds and 32 oz (1 L) in 90 seconds and has a built in lithium ion battery that has enough power to run 100-200 cycles before it runs out.
The benefit of this product over the SteriPen is that it's more affordable so you can save yourself some money. The downside of this product is that is not a brand name product so you need to trust the Amazon reviews a bit more and there is less information on this brand in general.
Click here to see the latest price of the UV Water Filter Pen at Amazon
6. Life Straw
The LifeStraw is a membrane micro-filter that filters out 99.999999% of bacteria (including E.coli, Salmonella), 99.999% of parasites (including Giardia and Cryptosporidium), 99.999% of micro-plastics, chlorine, organic chemical matter and turbidity.
This product started out as a humanitarian product to help people in countries that lacked clean drinking water. Because it removes bacteria and parasites this product can be a lifesaver to many people.
If you're traveling and you want to filter the water from your Hydro Flask then you could use a LifeStraw as well.
It works in the same was as the Epic Water Filter as well as the AquaMira water filters.
The LifeStraw contains lots of little straws that have holes that are just 0.2 microns. This allows water molecules to pass through, but it doesn't all bacteria or parasites to pass through.
Below you can see a video showing the effectiveness of the LifeStraw under a microscope.
One important thing to note is the LifeStraw won't filter out viruses so if you're drinking water from an area that has viruses you'll either need a UV filter like the HydroCap or a filter like the AquaMira that can filter out viruses too.
But a benefit of the LifeStraw over the UV filter is that it'll filter out a lot of the sediment as well, so it can be used in silty water where UV filters won't work.
It will filter approximately 1,000 gallons (3,785 L) before it needs to be replaced and they are extremely affordable at around $10-$15 each and you can buy them in bulk too.
They are small, lightweight and easy to carry with you.
See the latest price of the LifeStraw at Amazon
7. At Home Solution – Mini UV-C Light
If you're looking for the most cost effective solution to filter the water in your Hydro Flask then this mini UV-C light could be a good at home solution for you.
It's designed to be used in fish tank filters but it'll do the trick to kill bacteria, protozoa and viruses in your water bottle as well.
Simply place the mini UV bulb inside your water bottle and turn it on. Refer to the instruction on how long to run it for but if it's as strong as the HydroCap or the SteriPen then 1.5-3 minutes should do the trick.
A really affordable solution to filter your Hydro Flask bottle at home before you go out.
It only uses 3 Watts of power and should last you years.